[217] CEPHALOPODS OF NORTHEASTERN COAST OF AMERICA. 427 



tact beneath; eye-lids thin, entire. The body is long, somewhat fusi- 

 form, slightly smaller in advance of the middle. The tissues are exceed- 

 ingly thin, delicate, pale, and translucent, so that the pen and other 

 organs can be seen through the mantle. Anteriorly the edge of the 

 mantle is directly attached to the head, medially, by a muscular com- 

 missure, and there is no free edge (such as D'Orbigny figures in Taonius 

 pavo) at the narrow middle portion of this band. This commissure is 

 broader within the mantle, and there is another large, oblique, muscular 

 commissure, extending forward to the edge of the mantle, on each side, 

 extensively uniting the inner surface of the mantle to the sides of the 

 siphon. These commissures leave only a rather narrow opening to the 

 gill-cavity, on each side, and one small ventral one, and the interior 

 ventral cavity is partitioned off from the lateral ones. 



The siphon is large, projecting forward between the lower sides of the 

 large eyes; it has no valve in the ordinary place, but toward the base, 

 on the dorsal side, there are two erect, rounded, ear-like flaps, each ac- 

 companied by a prominent papilla (i'), and farther forward a raised, me- 

 dian, transverse fold, and a central papilla (i). (Plate XLV, fig. 2d.) 



The caudal fin is comparatively small, narrow-ovate, tapering to a 

 short, blunt posterior end, and with the anterior lobes narrowed and 

 scarcely projecting beyond the insertions. 



Arms rounded, rather slender, tapering to slender tips; those of the 

 third pair are much the longest, and like the second pair, bear along 

 the distal half suckers much larger than the proximal ones; tips short, 

 with few small suckers. The dorsal and ventral arms are about equal, 

 and not much more than half as long as the third pair; they bear smaller 

 suckers, in two rows, regularly decreasing distally. The second pair is 

 intermediate in length between the first and third pairs, with two rows 

 of larger suckers on the outer half, suddenly decreasing distally, with 

 minute ones close to the tip. The large suckers (fig. 2 b, 2c) on the second 

 and third pairs of arms are much larger than the others, but similar in 

 form, deep cup-shaped, convex in the middle, obliquely attached, with 

 a smooth horny rim, except on the distal ones, which have blunt denti- 

 cles externally. There are about sixteen of these suckers on each of 

 the lateral arms, but eight or ten are decidedly larger than the rest. 

 The large suckers commence nearly at the middle of the arms and ex- 

 tend to very near the tips. The third pair of arms have a thin median 

 carina on the outer side, along the distal third. All the arms have a 

 wide marginal or protective membrane along the inner edges, outside 

 the suckers; these membranes are strengthened by transverse thick- 

 ened, muscular processes, opposite each sucker; between these the mem- 

 brane recedes so that the edge is scolloped. The ventral arms have 

 also a membrane along the outer, ventral angle. I am unable to detect 

 any positive signs of hectocotylization, either in the dorsal or ventral 

 arms. Perhaps the presence of the very large suckers on the lateral 

 arms may be a sexual character, but if so, they are symmetrical on the 

 two sides. 



